Extended depth-of-field (EDOF) provides camera users with an increased range over which objects are in focus. However, this range comes at the cost of a drop in modulation transfer function (MTF) at a given range of conjugates. The traditional method of solving this problem is by providing cameras with an aperture stop with controllable diameter, such as an iris. However, an iris requires a large, bulky and relatively expensive element that is practical only in large cameras, and is not practical in ultra-compact cameras, such as cell phone cameras. Also, an iris achieves an increased depth of field by effectively increasing the lens focal ratio, with a corresponding result of reducing the amount of light reaching the lens and camera sensor by an amount proportional to the reduction in the area of the aperture. Thus, there is a need for systems and methods capable of providing camera users with variable amounts of EDOF with enough flexibility to adapt to different imaging situations.
The following U.S. Patents provide information about wavefront coding, and are incorporated by reference in their entireties: U.S. Pat. Nos. 5,748,371, 6,525,302, 6,842,297, 6,911,638, 6,940,649, 7,115,849, 7,180,673, 7,218,448, 7,260,251, 7,379,613.